the gas that is directly in contact with them, this equilibrium | two principal forms, the spindle-rooted and the turnipwould be the actual state of affairs; and it would follow rooted. from the principle of Archimedes that, when extraneous forces such as gravity are not considered, the gas would exert no resultant force on any body immersed in it. On this ground Maxwell inferred that the forces acting in the radiometer are connected with gliding of the gas along the unequally heated boundaries; and as the laws of this slipping, as well as the constitution of the adjacent layer, are uncertain, the problem becomes very intricate. Such slipping had shown itself at high exhaustions in the experiments of A. A. Kundt and E. G. Warburg in 1875 on the viscosity of gases; its effects would be corrected for, in general, by a slight effective addition to the thickness of the gaseous layer.

separated with another active substance-radium; whilst a third | "radiant," "radiation," and allied words. In mathematics, a fraction, composed mainly of the rare earths (thorium, &c.), radius is a straight line drawn from the centre to the circumyielded to Debierne another radioactive element-actinium, ference of a circle or to the surface of a sphere; in anatomy which proved to be identical with the emanium of Giesel. the name is applied to the outer one of the two bones of the Another radioactive substance-ionium--was isolated from car- fore-arm in man or to the corresponding bone in the fore-leg of notite, a uranium mineral, by B. B. Boltwood in 1905. Radio- animals. It is also used in various other anatomical senses in active properties have also been ascribed to other elements, e.g. botany, ichthyology, entomology, &c. A further application of thorium and lead. There is more radium than any other radio- the term is to an area the extent of which is marked by the active element, but its excessive rarity may be gauged by the length of the radius from the point which is taken as the centre; facts that Mme. Curie obtained only a fraction of a gramme of thus, in London, for the purpose of reckoning the fare of hackneythe chloride and Giesel 2 to 3 gramme of the bromide from a carriages, the radius is taken as extending four miles in any ton of uranium residues. direction from Charing Cross.

There is a mass of evidence to show that radium is to be regarded as an element, and in general its properties resemble those of the metals of the alkaline earths, more particularly barium. To the bunsen flame a radium salt imparts an intense carmine-red colour (barium gives a green). The spectrum, also, is very characteristic. The atomic weight, 226-4, places the element in a vacant position in group II. of the periodic classification, along with the alkaline earth metals.

Generally speaking, the radiation is not simple. Radium itself emits three types of rays: (1) the a rays, which are regarded as positively charged helium atoms; these rays are stopped by a single sheet of paper; (2) the ẞ rays, which are identified with the cathode rays, i.e. as a single electron charged negatively; these rays can penetrate sheets of aluminium, glass, &c., several millimetres thick; and (3) the y rays-which are non-electrified radiations characterized by a high penetrating power, 1% surviving after traversing 7 cm. of lead or 150 cm. of water. In addition, radium evolves an "emanation" which is an extraordinarily inert gas, recalling the "inactive" gases of the atmosphere. We thus see that radium is continually losing matter and energy as electricity; it is also losing energy as heat, for, as was observed by Curie and Laborde, the temperature of a radium salt is always a degree or two above that of the atmosphere, and they estimated that a gramme of pure radium would emit about 100 gramme-calories per hour.

RADNOR, EARLS OF. The 1st earl of Radnor was John Robartes (1606-1685), who succeeded his father, Richard Robartes, as 2nd baron Robartes of Truro in May 1634, the barony having been purchased under compulsion for £10,000 in 1625. The family had amassed great wealth by trading in tin and wool. Educated at Exeter College, Oxford, John Robartes fought on the side of the Parliament during the Civil War, being present at the battle of Edgehill and at the first battle of Newbury, and was a member of the committee of both kingdoms. He is said to have persuaded the earl of Essex to make his ill-fated march into Cornwall in 1644; he escaped with the earl from Lostwithiel and was afterwards governor of Plymouth. Between the execution of Charles I. and the restoration of Charles II. he took practically no part in public life, but after 1660 he became a prominent public man, owing his prominence partly to his influence among the Presbyterians, and ranged himself among Clarendon's enemies. He was lord deputy of Ireland in 1660-1661 and was lord lieutenant in 16691670; from 1661 to 1673 he was lord privy seal, and from 1679 to 1684 lord president of the council. In 1679 he was created viscount Bodmin and earl of Radnor, and he died at Chelsea on the 17th of July 1685. His eldest son, Robert, viscount Bodmin, who was British envoy to Denmark, having predeceased his father, the latter was succeeded as 2nd earl by his grandson, Charles Bodvile Robartes (1660-1723), who was a member of The Becquerel rays have a marked chemical action on certain parliament under Charles II. and James II., and was lord substances. The Curies showed that oxygen was convertible lieutenant of Cornwall from 1696 to 1705 and again from 1714 into ozone, and Sudborough that yellow phosphorus gave the to 1723. Henry, the 3rd earl (c. 1690-1741), was also a grandred modification when submitted to their influence. More son of the 1st earl, and John, the 4th earl (c. 1686-1757), was interesting are the observations of D. Berthelot, F. Bordas, another grandson. When John, whose father was Francis C. Doelter and others, that the rays induce important changes Robartes (c. 1650-1718), a member of parliament for over in the colours of many minerals. (See RADIOACTIVITY.) thirty years and a musician of some repute, died unmarried in July 1757, his titles became extinct.

The action of radium on human tissues was unknown until 1901, when, Professor Becquerel of Paris having incautiously carried a tube in his waistcoat pocket, there appeared on the skin within fourteen days a severe inflammation which was known as the famous "Becquerel burn." Since that time active investigation into the action of radium on diseased tissues has been carried on, resulting in the establishment in Paris in 1906 of the "Laboratoire biologique du Radium." Similar centres for study have been inaugurated in other countries, notably one in London in 1909. The diseases to which the application has been hitherto confined are papillomata, lupus vulgaris, epithelial tumours, syphilitic ulcers, pigmentary naevi, angiomata, and pruritus and chronic itching of the skin; but the use of radium in therapeutics is still experimental. different varieties of rays used are controlled by the intervention of screens or filtering substances, such as silver, lead or aluminium. Radium is analgesic and bactericidal in its action. See Radiumtherapie, by Wickham and Degrais (1909); Die therapeutische Wirkung der Radiumstrahlen, by O. Lassar, in Report of Radiology Congress, Brussels, 1906; E. Dorn, E. Baumann and S. Valentiner in Physische Zeitung (1905); Abbé in Medical Record (October 1907).

The

RADIUS, properly a straight rod, bar or staff, the original meaning of the Latin word, to which also many of the various meanings seen in English were attached; it was thus applied to the spokes of a wheel, to the semi-diameter of a circle or sphere and to a ray or beam of light, "ray" itself coming through the Fr. raie from radius. From this last sense comes

Lanhydrock, near Bodmin, and the other estates of the Robartes family passed to the earl's nephews, Thomas and George Hunt. Thomas Hunt's grandson and heir, Thomas James Agar-Robartes (1808-1882), a grandson of an Irish peer, James Agar, 1st viscount Clifden (1734-1789), was created baron Robartes of Lanhydrock and of Truro in 1869, after having represented East Cornwall in seven parliaments. His son and successor, Thomas Charles Agar-Robartes, the 2nd baron (b. 1844), succeeded his kinsman as 6th viscount Clifden in 1899.

In 1765 William Bouverie, 2nd viscount Folkestone (17251776), son of Sir Jacob Bouverie, bart. (d. 1761), of Longford, Wiltshire, who was created viscount Folkestone in 1747, was made earl of Radnor. Descended from a Huguenot family, William Bouverie was a member of parliament from 1747 until he succeeded to the peerage in February 1761. He died on the 28th of January 1776. His son and successor, Jacob, the 2nd earl (1750-1828), who took the name of PleydellBouverie in accordance with the will of his maternal grandfather, Sir Mark Stuart Pleydell, bart. (d. 1768), was the father of William Pleydell-Bouverie, the 3rd earl (1779-1869), a politician of some note. In 1900 his great-grandson, Jacob Pleydell-Bouverie (b. 1868), became 6th earl of Radnor.

RADNORSHIRE (Sir Faesyfed), an inland county of Wales, bounded N. by Montgomery, N.E. by Shropshire, E. by Hereford, S. and S.W. by Brecknock and N.W. by Cardigan. This county, which is lozenge-shaped, contains 471 sq. m., and is

included in the South Wales circuit, and assizes are held at Presteign, which ranks as the county town. There is no existing parliamentary borough, and the whole county returns. one member to parliament. Ecclesiastically, Radnorshire is divided into 46 parishes, of which 38 lie in the diocese of St Davids, and 8 in that of Hereford.

consequently the smallest in area of the six South Welsh | all, except Rhayader, being urban districts. Radnorshire is counties. Nearly the whole surface of Radnorshire is hilly or undulating, whilst the centre is occupied by the mountainous tract known as Radnor Forest, of which the highest point attains an elevation of 2163 ft. Towards the S. and S.E. the hills are less lofty, and the valleys broaden out into considerable plains abounding in rivulets. The hills for the most part present smooth, rounded outlines, and are covered with heather, bracken and short grass, though tracts of boggy soil in the uplands are not uncommon. There are rich pastures and numerous woods in the valleys of the Wye and Teme. The Wye Valley has long been celebrated for its beauty, while Radnor Forest and the wild district of Cwmdauddwr present striking views of primeval and unspoiled scenery. Radnorshire is well supplied with water, its principal river being the Wye (Gwy), which, after crossing the N.W. corner of the county, forms its boundary from Rhayader onward to the English border. Salmon, trout and grayling are plentiful, and the Wye is consequently much frequented by anglers; as are also its tributaries-the Elan (which has been utilized for the great Birmingham reservoirs) the Ithon, the Edw or Edwy, the Lug, the Arrow and the Somergil. The Teme, which divides Radnor from Shropshire on the N.E., is a tributary of the Severn. All these streams are clear and rapid, and abound in fish. In the numerous rocky ravines of the mountainous districts are found many waterfalls, of which the most celebrated is "Water-break-its-Neck," to the W. of New Radnor. Omitting the artificially constructed reservoirs in the valleys of the Elan and Claerwen, the lakes of Radnorshire are represented only by a few pools of which Llynbychlyn near Painscastle is the largest.

Geology.-Ordovician rocks occupy most of the western side of the county, they are succeeded eastward by the Silurian formations, the Llandovery, Wenlock and Ludlow beds in the order here given. East of New Radnor an inlier of Wenlock rocks is surrounded by Ludlow beds; while at Old Radnor a ridge of very ancient rocks appears. In the south-east of the county Old Red Sandstone rests upon the Silurian. Between Llandrindod, where there are saline, sulphurous and chalybeate wells, and Builth, is a disturbed area of Ordovician strata with masses of andesitic and diabasic igneous rocks. In the vicinity of Rhayader the strata have been classed as the Rhayader pale shales (Tarannon), the Caban group (Upper Llandovery), the Gwastaden group (Lower Llandovery); these rest upon shales of Bala age. Climate and Industries.-The climate of Radnorshire is bracing, if somewhat bleak, and the rainfall is not so heavy as in the neigh bouring counties of Montgomery and Brecknock, but thick drizzling mists are of constant occurrence. The winters are often very severe, and deep snowfalls are not uncommon. Good hay and tolerable crops of cereals are raised in the valleys, and the margin of cultivation has risen considerably since 1880. The extensive upland tracts, which still cover over one-third of the total area of the county, afford pasturage for mountain ponies and for large flocks of sheep. The quality of the wool of Radnorshire has long been celebrated, and also the delicacy of the Welsh mutton of the small sheep that are bred in this county. The most important sheep fairs are held at Rhayader, which also contains some woollen factories. There are practically no mining industries, nor are the quarries of great value. The valley of the Wye is rich in medicinal springs, and the saline, sulphur and chalybeate waters of Llandrindod have long been famous and profitable, and are growing in popular esteem.

Communications.-The Central Wales branch of the London & North-Western railway enters the county at Knighton, traverses it by way of Llandrindod and passes into Brecknock at Builth Road Junction on the Wye. The Cambrian railway, after passing through the N.W. corner of the county to Rhayader, follows the course of the Wye, by way of Builth and Hay. Two small branch lines connect New Radnor and Presteign with the system of the Great Western.

Population and Administration.-The area of Radnorshire is 301,164 acres, and the population in 1891 was 21,791, while in 1901 it had risen to 23.362; an increase chiefly due to the immigration of outside labourers to the Elan Valley waterworks. There is no existing municipal borough, although New Radnor, now a mere village with 405 inhabitants (1901), was incorporated in 1561 and its municipal privileges were not formally abolished till 1883. The chief towns are Presteign (pop. 1245); Llandrindod (1827); Knighton (2139), and Rhayader (1215); |

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History. The wild district of Maesyfed (a name of which the derivation is much disputed), corresponding substantially with the modern Radnorshire, originally formed part of the territory of the Silures, who were vanquished by the Romans. Christianity seems to have been introduced into this barren region during the 5th and 6th centuries by itinerant Celtic missionaries, notably by St David, St Padarn and St Cynllo. Towards the close of the 9th century Maesyfed was absorbed into the middle kingdom of Powys, and in the 10th century it was included in the realm of Elystan Glodrudd, prince of Fferlys, or Feryllwg, who ruled over all land lying between the Wye and Severn. In the reign of William the Conqueror, the Normans began to penetrate into Maesyfed, where, according to Domesday Book, the king already laid claim to Radenoure, or Radnor (a name of doubtful meaning), in the lordship of Melenith (Moelynaidd), which was subsequently bestowed on the Mortimer family, when castles were erected at Old Radnor (Penygraig), New Radnor and Cefnllys. Later, the Norman invaders forced their way up the Wye Valley, the de Breos family, lords of Elvel (Elfael), building fortresses at Painscastle and at Colwyn or Maud's Castle. In 1188 Archbishop Baldwin, accompanied by Ranulf de Glanville and Giraldus Cambrensis, entered Wales for the purpose of preaching the Third Crusade, and was met in full state at New Radnor by the Lord Rhys, prince of South Wales. The Wye Valley long formed one of the debatable districts between Welsh and Normans, and in 1282 Llewelyn ap Griffith, prince of Wales, was at Aberedw shortly before his death in a skirmish near Builth. After the annexation of Wales by Edward I., the district of Maesyfed remained under the immediate jurisdiction of the Lords-Marchers, represented by the great families of Mortimer and Todeney. During the summer of 1402 Owen Glendower entered the Marches and raided the lands of the young Edward Mortimer, earl of March, whilst the royal troops were severely defeated at the battle of Bryn Glâs near Pilleth. By the Act of Union (1536) Maesyfed was erected out of the suppressed lordships into an English shire on the usual model. For administrative purposes it was now divided into six hundreds, and assizes were ordained to be held in alternate years at Presteign and New Radnor. The newly created county was likewise privileged to return two members to parliament; one for the county, and one for the united boroughs of New Radnor, Rhayader, Knighton, Cefnllys and Knucklas (Cnwclas). The parliamentary district of the Radnor boroughs was, however, disfranchised and merged in the county representation under the act of 1885. The shire of Radnor with its immense tracts of sheep-walk, its absence of large towns and its sparse rural population has always been reckoned the poorest and least important of the Welsh counties, nor since its creation under Henry VIII. has it ever played a prominent part in the national life of Wales. During the Commonwealth the local clergy were made to suffer severely under the drastic administration of Vavasor Powell (1617-1670), himself a Radnorshire man as a native of Knucklas. Of recent years the rise of Llandrindod as a fashionable watering-place and the construction of the Birmingham reservoirs in the Elan Valley have tended to increase the material prosperity of the county.

Among the leading families of Radnorshire, may be mentioned Lewis of Harpton Court; Baskerville of Clyro; Thomas (formerly Jones) of Pencerrig; Lewis-Lloyd of Nantgwyllt; Gwynne of Llanelwedd, and Prickard of Dderw.

Antiquities.-Radnorshire contains numerous memorials of early British times, of which the entrenchment called Crug-ybuddair in the parish of Beguildy is specially worthy of note. Of Roman remains, the most important are those of the fortified camp at Cwm near Llandrindod, which is believed to be identical

he was appointed minister of foreign affairs. He resigned, He was early left an orphan. Being placed in Heriot's Hospital, however, on the 2nd of November, owing to the king's refusal to settle the difficulties with Austria by an appeal to arms. In August 1852 he was appointed director of military education; but the rest of his life was devoted mainly to literary pursuits. He died on the 25th of December 1853.

he received there the elements of a sound education, and at the age of fifteen was apprenticed to a goldsmith in Edinburgh. Here he had some little opportunity for the practice of the humbler kinds of art, and various pieces of jewelry, mourning rings, and the like, adorned with minute drawings on ivory Radowitz published, in addition to several political treatises, by his hand, are still extant. Soon he took to the production Ikonographie der Heiligen, ein Beitrag zur Kunstgeschichte (Berlin, of carefully finished miniatures; and, meeting with success 1834) and Devisen und Mottos des spätern Mittelalters (ib., 1850). and patronage, he extended his practice to oil-painting, being His Gesammelte Schriften were published in 5 vols. at Berlin, 1852-53. all the while quite self-taught. The worthy goldsmith his See Hassel, Joseph Maria von Radowitz (Berlin, 1905, &c.). master watched the progress of his pupil with interest, gave RAE, JOHN (1813-1893), Scottish Arctic explorer, was born him every encouragement, and introduced him to David Martin, on the 30th of September 1813, in the Orkney Islands, which who had been the favourite assistant of Allan Ramsay junior, he left at an early age to study medicine at Edinburgh Uni- and was now the leading portrait-painter in Edinburgh. Raeversity, qualifying as a surgeon in 1833. He made a voyage burn received considerable assistance from Martin, and was in a professional capacity in one of the ships of the Hudson's especially aided by the loan of portraits to copy. Soon the Bay Company, and entering the service of the company was resident surgeon for ten years at their station at Moose Factory, that he should devote himself exclusively to painting. When he young painter had gained sufficient skill to render it advisable at the head of James Bay. In 1846 he made a boat-voyage was in his twenty-second year he was asked to paint the portrait to Repulse Bay, and having wintered there, in the following of a young lady whom he had previously observed and admired spring surveyed 700 miles of new coast-line connecting the when he was sketching from nature in the fields. She was the earlier surveys of Ross and Parry. An account of this expedi- daughter of Peter Edgar of Bridgelands and widow of Count tion, A Narrative of an Expedition to the Shores of the Arctic Leslie. The lady was speedily fascinated by the handsome and Sea in 1846 and 1847, was published by him in 1850. During intellectual young artist, and in a month she became his wife, a visit to London in 1848 he joined the expedition which was bringing him an ample fortune. This early insurance against then preparing to go out under Sir John Richardson in search the risks of his chosen profession, did not, however, diminish of Franklin; and in 1851, at the request of the Government his anxiety to excel. The acquisition of wealth affected neither and with a very slender outfit, he travelled some 5300 miles, his enthusiasm nor his industry, but rather spurred him to much of it on foot, and explored and mapped 700 miles of new greater efforts to acquire a thorough knowledge of his craft. coast on the south side of Wollaston and Victoria Lands. For After the approved fashion of artists of the time, it was resolved this achievement he received the Founder's gold medal of the that Raeburn should visit Italy, and he accordingly started Royal Geographical Society. In 1853 he commanded another with his wife. In London he was kindly received by Sir Joshua boat-expedition which was fitted out by the Hudson's Bay Reynolds, who gave him excellent advice as to his study in Company, which connected the surveys of Ross with that of Rome, especially recommending to his attention the works of Deane and Simpson, and proved King William's Land to be Michelangelo. He also offered him more substantial pecuniary an island. It was on this journey that he obtained the first aid, which was declined as unneeded; but Raeburn carried authentic news regarding the fate of Franklin, thereby winning with him to Italy many valuable introductions from the the reward of £10,000 promised by the admiralty. He sub-president of the Academy. In Rome he made the acquaintance sequently travelled across Iceland, and in Greenland and the of Gavin Hamilton, of Batoni, and of Byers. For the advice northern parts of America, surveying routes for telegraph lines. of the last-named he used to acknowledge himself greatly Dr Rae attributed much to his success in Arctic travel to his indebted, particularly for the recommendation that "he adoption of the methods of the Eskimo, a people whom he should never copy an object from memory, but, from the had studied very closely. He was a keen sportsman, an principal figure to the minutest accessory, have it placed before accurate and scientific observer. He died at his house in London him." After two years of study in Italy he returned to Edinand was buried in the Orkney Islands. burgh in 1787, where he began a most successful career as a portrait-painter. In that year he executed an admirable seated portrait of the second Lord President Dundas.

RAE BARELI, a town and district of British India, in the Lucknow division of the United Provinces. The town is on the river Sai, 48 m. S.E. of Lucknow, on the Oudh & Rohilkhand railway. Pop. (1901) 15,880. It possesses many architectural features, chief of which is a strong and spacious fort erected in 1403, and constructed of bricks 2 ft. long by 1 ft. thick and wide. Among other ancient buildings are the magnificent palace and tomb of nawab Jahan Khan, governor in the time of Shah Jahan, and four fine mosques. The town is an important centre of trade, and muslins and cotton cloth

are woven.

The DISTRICT OF RAE BARELI has an area of 1748 sq. m. The general aspect of the district is slightly undulating, and the country is beautifully wooded. The soil is remarkably fertile, and the cultivation of a high class. The principal rivers of the district are the Ganges and the Sai: the former skirts it for 54 miles and is everywhere navigable for boats of 40 tons; the latter traverses it from N.W. to S.E. In 1901 the population was 1,033,761, showing a slight decrease during the decade. The principal crops are rice, pulse, wheat, barley, millet and poppy. Rae Bareli town is connected with Lucknow by a branch of the Oudh & Rohilkhand railway, which in 1898 was extended to Benares.

See Rae Bareli District Gazetteer, Allahabad, 1905.

RAEBURN, SIR HENRY (1756-1823), Scottish portraitpainter, was born at Stockbridge, a suburb of Edinburgh, on the 4th of March 1756, the son of a manufacturer of the city.

Of his earlier portraiture we have interesting examples in the bust-likeness of Mrs Johnstone of Baldovie and in the three-quarter-length of Dr James Hutton, works which, if they are somewhat timid and tentative in handling and wanting ir the trenchant brush-work and assured mastery of subsequent productions, are full of delicacy and character. The portraits of John Clerk, Lord Eldin, and of Principal Hill of St Andrews belong to a somewhat later period. Raeburn was fortunate in the time in which he practised portraiture. Sir Walter Scott, Blair, Mackenzie, Woodhouselee, Robertson, Home, Ferguson, and Dugald Stewart were resident in Edinburgh, and they all, along with a host of others less celebrated, honoured the painter's canvases. Of his fully matured manner we could have no finer examples than his own portrait and that of the Rev. Sir Henry Moncrieff Wellwood, the bust of Dr Wardrop of Torbane Hill, the two full-lengths of Adam Rolland of Gask, the remarkable paintings of Lord Newton and Dr Alexander Adam in the National Gallery of Scotland, and that of William Macdonald of St Martin's. It was commonly believed that Raeburn was less successful in his female than in his male portraits, but the exquisite full-length of his wife, the smaller likeness of Mrs R. Scott Moncrieff in the Scottish National Gallery, and that of Mrs Robert Bell, and others, are sufficient to prove that he could portray all the grace and beauty of the gentler sex.